18f39f940b
- Add nil service guards to Register/Deregister/Renew in gRPC and HTTP plugins to prevent nil pointer dereferences - Remove unused log field from grpcPlugin and httpPlugin - Prefix HTTP error messages with operation context (sd register/deregister/renew/get) - Return gRPC Register error directly instead of logging + returning - Add 33 unit tests covering all operations, nil guards, and error paths